Electrical terminal structure



Oct.6,19 70 ags E-rAL 3,533,054

ELECTRICAL TERMINAL s'rnuc'runn Filed 001:. a, 1968 42. r 40 26 FIG 8 1"INVENTORS ALBERT SPRIGGS BY THOMAS 5 MANCINI ATTORNEY United StatesPatent 3,533,054 ELECTRICAL TERMINAL STRUCTURE Albert Spriggs and ThomasMancini, Hamilton, Ontario,

Canada, assignors to United-Carr Incorporated, Boston, Mass., acorporation of Delaware Filed Oct. 8, 1968, Ser. No. 765,767 Claimspriority, application Canada, Jan. 11, 1968, 59

Int. Cl. H01r 9/08, 11/08 US. Cl. 339-221 2 Claims ABSTRACT OF THEDISCLOSURE This invention relates to an electrical terminal structure ofthe serrated bayonet type of improved capability of fabrication assemblyand resistance to breakage.

Serrated bayonet type electrical terminal devices are well known. Theyare usually characterized by a tubular or fiat copper, bronze or brassterminal member having thereon barb means such as serrated teethprojecting therefrom to engage surfaces of an accommodating recess orsocket in an electrical insulating carrier member. Heretofore thecarrier member has been formed from plastic materials of essentialinsulating properties and mechanical strength. Phenol resins have been apopular and natural choice for such applications. The mouldingproperties of phenol resins are particularly satisfactory and beingespecially inexpensive are widely used for electrical terminal mountingsespecially in connectors, switch gear, relay components, coil supportsand the like.

'It has been observed according to this invention that phenolic plasticmaterials such as may be well known by the trademark Bakelite, exhibit alow internal viscosity and relatively high rigidity or low order ofelasticity to the extent that the same are ordinarily regarded assomewhat brittle. Brittleness is controlled by the inclusion ofsubstantial filler material which reduces cost and increases resistanceto mechanical shock. Nevertheless the characteristics of such materialunder continuous stress will lead to cracking, warping and failure ofinsulating properties. Thus the proper electrical use of a low internalviscosity, low order of elasticity of material such as derived forelectrical applications from phenolic glass resins should avoid stressor deformation of any kind in connecting a terminal to an insulate bodyof such material. In spite of the fact that such information is known tomany skilled persons serrated bayonet type terminal devices have beeninserted into sockets within phenolic class supports for probably morethan fifty years. The immediate failure of the brittle support has beenavoided by substantial use of filler material. However, the basiccharacteristics of such a support material do not provide any resistanceto grip the terminal other than that available from the filler materialused. Thus such terminal assemblies have a propensity for shaking loosein use. Of the bayonet type of terminals the split hollow tube providingoutward elastic pressure against the walls of the receiving socket isthe more satisfactory in its endurance under vibration or disturbingforce.

It is, the main object of this invention to provide a bayonet typeelectrical terminal device of fiat strip form adapted to endure heavyvibration or disturbing forces 3,533,054 Patented Oct. 6, 1970 p ice bysupport under elastic tension in an elastomer insulating material ofhigh internal viscosity such as may be derived for example, from vinylclasses of resins, such as polyvinyl chloride and other forms having astrain memory or ability to recover a moulded form when distortedtherefrom such as materials known by the trade names nylon, Dacron andOrlon.

It is a further object of the invention to provide an electricalterminal structure especially for coil end supports which is adapted tobe moulded in a two part mould without necessitating socket withdrawalinserts thus to take advantage of elastic properties of the elastomermaterial used.

Other objects of the invention will be apparent from a study of thefollowing specification taken in conjunction with the accompanyingdrawings wherein:

FIG. 1 is a perspective view of a coil wound upon a core form or spoolhaving coil form ends carrying the terminal structure of the invention;

FIG. 2 is an enlarged exploded view of right hand fragment of FIG. 1;

FIG. 3 is an elevation of the assembled components of FIG. 2;

FIG. 4 is a section of the line 4-4 of FIG. 3;

FIG. 5 is a perspective elevation of prior art structure;

FIG. 6 is a view similar to FIG. 5 but of structure of the inventionsectioned as at line 6-6 of FIG. 4;

FIG. 7 illustrates a two-piece die technique for moulding the terminalsupport of the invention; and

FIG. 8 is section on the line 8 8 of FIG. 2.

In FIG. 1 an ordinary but not exclusive use of the invention is shown.Coil winding 10 wound upon core 11 extends between core ends (sometimesreferred to in the art as spool ends, core end plates, end supports orflanges) 12 and 13. It is convenient to form such spool ends of aninsulating material not only to assist in protecting coil 10 but also toprovide a suitable insulate support for making electrical connection ofcoil wires 14 and 15 to suitable terminals 16 which may be mounted onthe one or both spool ends. In many other electrical applications a coilassociated with spool ends requires terminal connections which are proofagainst shock vibration and aging.

As described above and referring in more detail to FIG. 5, a fiat stripserrated bayonet type connector 17 of the prior art presents rearwardlyflaring spur elements 18 adapted by their sharp pointed spur tips 19 tophysically scrape rigid surfaces 20 of a hexahedral socket 21 whichusually is in the form of a closed. socket having one entrance openingonly but which in the present instance is shown in a mouldable form withan open face 22. Such prior art connection is not generally used exceptin short life connections where no vibration or shock is expected. Theform is exceptionally inexpensive to manufacture especially where socket21 is open-faced as shown permitting a two piece forming die withinretractable inserts.

The present invention is addressed to the problem of such prior artclass of connector and realises its modification and application to longlife connections adapted to endure heavy vibrations and shock. Thus inFIGS. 2 to 4 and 6 and 8 the connector of the invention embodies aserrated bayonet type rigid metal strip 23 having rearwardly flaringspur elements 24 with slightly radiused spur tips or retaining shoulders25 to press into the material of the terminal support 26 in the regionof the dovetail surfaces 27 of open sided dovetail socket 28. Outer freeportions 29 of outwardly converging dovetail surfaces 27 substantiallyoverlie the outer or exposed surfaces 30 of the connector. Thus theconnector 23 cannot be moved laterally out of the retaining dovetailsocket. The connector support 26 is made according to this inventionfrom an insulate elastomer of high internal viscosity and relativelyhigh rigidity characterized by strain memory such as a polyvinylchloride and similar thermosetting materials having a strain memory.

A two piece moulding techniques may be employed as shown in FIG. 7 byproviding cavities 31, 32 and 33, 34 in mould plates 35, 36 embodyingmale dovetail portions 37 adapted upon separation of mould plates 35, 36by arrows 38, 39 to separate from the moulded part by flexing of thelatter thereabout due to sliding of surfaces 30 thereover. The partsection formed is shown in FIG. 8 and demonstrates a slot opening 40formed at a transverse angle of 45 degrees about a right angular mouldparting line 41. In addition a spur retaining boss 42 is simultaneouslyformed with a ramp surface 43 adapted to accommodate the insertion of aterminal strip thereover to a socket seated position as shown in FIGS. 3and 4 at which boss 42 projects into backing aperture 44 of theelectrode 23 As indicated in FIG. 6, the material of the supportgradually flows toward and about the retaining shoulder 25 rendering theterminal mounting eifectively permanent after a period of days, weeks ormonths depending upon the rigidity of the material. This action howeveris not essential during the early life of the connector mounting but isrequired only to the extent that the socket effectively increases itssupport over a period of time by virtue of the memory characteristic ofthe material as contrasted with the prior art form of support socketopening up due to shrinkage and cracking.

The invention provides a successful connector and support for a largevariety of applications in which strip bayonet connectors could not beused heretofore.

We claim:

1. In an electrical terminal structure of the flat-bayonet type: aterminal bayonet strip having rearwardly flared spurs thereon eachterminating in an outward gripping shoulder of small radius; an insulateelastomer supporting body of high internal viscosity having physicalproperties under strain adapted for cold flow to recover an unstrainedshape; and an open-faced terminal socket in said body having surfaces instrain engagement accommodating said shoulders at least of said stripinserted therein, and said socket is of dovetail form in sectionpresenting outwardly converging surfaces overlying a substantial portionof said terminal inserted therein.

2. The structure of claim 1 and a ramped backing boss in said socket andcorresponding backing means in said strip engageable thereby to retainsaid strip in said socket.

References Cited UNITED STATES PATENTS 1,997,198 4/1935 Ogg. 2,015,4219/1935 Eckstein et al 173-361 2,318,485 5/1943 Herman 33959 2,734,1772/1956 Gilbert 339-97 MARVIN A. CHAMPION, Primary Examiner R. A. HAFER,Assistant Examiner

